Abstract
Embedded bodies in a conveyor belt at intervals in a longitudinal direction each include a passive IC tag 3 at one side portion of the conveyor belt and a linear shaped detection element connected to the IC tag extending toward the other side portion to form a loop circuit. An embedding depth of the loop circuit into the conveyor belt is preset in advance, a transmission radio wave is emitted from a detector toward the IC tag, energization of the loop circuit 9 is determined using information transmitted from the IC tag to the detector via a return radio wave W 2 emitted from the IC tag 3 in response to the transmission radio wave, and to determine a degree of wear on the surface of the conveyor belt in a range where the loop circuit 9 is embedded.